The graph showing the relationship between the change in the detection rate on panoramic radiographs and maxillary sinus septal height. The X-axis is the height of septa in the maxillary sinus. The Y-axis is the detection rate of septa in the maxillary sinus on panoramic radiographs. With decreasing height of the septa in the maxillary sinus, the detection rate on panoramic radiographs increases gradually. The threshold for less clear visualization of the septa is at a height of about 5 mm (arrow).